PIP

I am on PIP lower rate for both, had a diagnosis of mixed dementia, so i advised them of change of circumstances , had a new form which i returned on the 24th sep, it had to be back on or before the 27th sep , Since that date i have heard nothing , but still been paid as before , is that normal not to hear anything in 2 months, or should i call them, thanks for any advice ,

thank you Gordon for all the info,